(1) Field of the Invention
The present invention is directed to buoyant cable antenna elements for use with underwater vehicles. In particular, the present invention is directed to a buoyant cable antenna specifically designed to provide broadband reception in the high frequency range.
(2) Description of the Prior Art
The buoyant cable antenna is one of a host of underwater vehicle antennas currently in use for radio communications while an underwater vehicle is submerged. A buoyant cable antenna consists of a straight insulated wire that is positively buoyant and designed to float to the ocean surface. The wire may be either a solid or stranded copper conductor of uniform diameter along its length. It is connected to the underwater vehicle by means of a standard coaxial transmission line at one end, and is terminated at the other end by means of either a shorting cap to connect it to the ocean or an insulating cap to isolate it from the ocean. The choice of cap is determined by the mode of operation that is needed. Prior art buoyant cable antennas suffer from limited performance in certain frequency bands due to the resonant behavior of the antenna element. Currently, there is a need for a means to improve the bandwidth of buoyant cable antennas through the use of discrete distributed loading along the antenna.